Effect of Heat on Multiple Barriers Penetration with Spark Discharge and Upward Leader in Air

摘要

When lightning strikes a wind power generator, it often penetrates the blades of wind power generator in spite of beingprotected from lightning by a receptor. In order to reduce such penetration damage, we have been studying the form of dischargeand the main factors of penetration. In our previous study, we made discharges penetrate insulator barriers placed between theelectrodes. As a result, equivalent radii calculated from areas of penetration holes varied depending on type of barriers. In thispaper, in order to confirm whether heat is related to the penetration of the insulator due to the discharge, barriers having differentmelting points were used. Then it was investigated whether equivalent radii of the penetration holes become larger with barriershaving lower melting point. In addition, we investigated effects of an upward leader on penetration holes generation by using ahigh-speed camera and a single-lens reflex camera. As a result, the equivalent radii of barriers with a high melting point and itwith a low melting point were approximately the same size, but microscope images of barriers suggested that spark dischargescould heat barriers. In addition, since no penetration holes were generated after only upward leader passed barriers, it wassuggested that upward leaders were low-temperature plasma.